CRED: Use RCU to access another task's creds and to release a task's own creds

[linux-2.6-block.git] / mm / mempolicy.c

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index b23492ee3e5072dbc74814bf06e9635de7f16422..7555219c535bfdad20f17f38223cb00271823c73 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1110,7 +1110,7 @@ asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode,
                const unsigned long __user *old_nodes,
                const unsigned long __user *new_nodes)
 {
-       struct cred *cred, *tcred;
+       const struct cred *cred = current_cred(), *tcred;
        struct mm_struct *mm;
        struct task_struct *task;
        nodemask_t old;
@@ -1145,14 +1145,16 @@ asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode,
         * capabilities, superuser privileges or the same
         * userid as the target process.
         */
-       cred = current->cred;
-       tcred = task->cred;
+       rcu_read_lock();
+       tcred = __task_cred(task);
        if (cred->euid != tcred->suid && cred->euid != tcred->uid &&
            cred->uid  != tcred->suid && cred->uid  != tcred->uid &&
            !capable(CAP_SYS_NICE)) {
+               rcu_read_unlock();
                err = -EPERM;
                goto out;
        }
+       rcu_read_unlock();
 
        task_nodes = cpuset_mems_allowed(task);
        /* Is the user allowed to access the target nodes? */